A method of controlling the content of a chemical bath includes the steps of: determining a replenishment condition for the chemical bath; defining a unit of the replenishment condition; establishing a pacing factor corresponding to a replenishment volume of a replenishment medium per unit of the replenishment condition; and defining a replenishment threshold corresponding to the product of a predetermined number of the defined units of the replenishment condition and the pacing factor. The rate of continued replenishment of the predetermined constituent of the chemical bath is determined in response to the replenishment condition, which may be elapsed time, ampere-hours (or coulombs), number of product loads, product surface area, or line speed over time. The method replenishes constituents as they actually are consumed. It also prevents depletion (or buildup in the case of decanting a by-product) and the associated time delay related to detection and correction. The method is effective in controlling a copper electroplating operation.

1. Field of the Invention
This invention relates generally to systems for maintaining a predetermined concentration or balance of chemical constituents in a chemical bath, and more particularly, to a system that replenishes chemical components in accordance with historical replenishment rates that are modified in response to chemical analysis of the chemical bath.
2. Background of the Prior Art
Known arrangements and methods for maintaining a predetermined concentration or balance of chemical constituents in a chemical bath employ a control system that uses both, feed-forward (i.e., predictive) and feed-backward control. The feed-backward control relies on sensor inputs relating to constituent concentrations, plating efficiency, current output from the rectifier, drag-out rate, plating solution volume/liquid level, temperature and plating thickness.
The feed-forward control relies on a predictive model. In the context of an electroplating process, the changes in composition of the plating bath due to anode and cathode reactions are quantitatively modeled as a function of current-time. Additionally, the changes through drag-out are also modeled as a function of current-time. These are combined to obtain an overall system model. Oftentimes, materials or mass balance equations are applied to the model to calculate replenishment as a function of current-time to compensate for the losses and to maintain constant bath composition.
Known arrangements employ a microprocessor to compare the sensor signals obtained by the feed-backward control sensors against set points obtained by the predictive model and control/tolerance limits. If the values exceed the control/tolerance limits, the system can (1) recommend additional replenisher additions; (2) recommend postponing upcoming fee-forward additions for a determined period of ampere-time; and/or (3) assist the user in bringing the bath parameters back into their desired ranges via diagnostic screens.
The known systems are complicated and not very accurate. There is a need for a system that is effective at adjusting an historical trend in replenishment additions, and which does not rely on adjustment of a predictive model to effect the replenishment.
The present invention, in a first aspect thereof, is in the form of a method of controlling the content of a chemical bath. This method aspect of the invention includes the steps of:
first determining a rate of continued replenishment of a predetermined constituent of the chemical bath;
second determining a replenishment condition for the chemical bath; and
adjusting the rate of continued replenishment of the predetermined constituent of the chemical bath in response to the replenishment condition.
The rate of continued replenishment in the step of first determining is based on an historical replenishment rate. The step of second determining a replenishment condition includes, in one embodiment of the invention, the step of monitoring elapsed time. In other embodiments, the step of second determining a replenishment condition includes, for example:
monitoring the consumption of electrical energy by the chemical bath;
monitoring the number of products to be plated in the plating bath; and/or
monitoring the surface area of the products to be plated in the plating bath.
In a further embodiment of the invention, the step of first determining a rate of continued replenishment includes the steps of:
first establishing a quantum of a replenishment medium; and
third determining a replenishment frequency corresponding to a rate at which the established quantum of a replenishment medium is deposited in the chemical bath with respect to the replenishment condition. This embodiment may further include the further steps of:
defining units of the replenishment condition; and
counting elapsed units of the replenishment condition.
In this embodiment, there is further provided the step of defining a replenishment threshold corresponding to the product of the defined units of the replenishment condition and a predetermined number of units of the replenishment condition. The step of adjusting the rate of continued replenishment includes the step of comparing a counted number of units of the replenishment condition to the predetermined number of units of the replenishment condition. Additionally, the step of adjusting the rate of continued replenishment includes the step of determining a rate of adjustment of the rate of continued replenishment.
In accordance with a further method aspect of the invention, there is provided a method of controlling the content of a chemical bath, the method comprising the steps of:
determining a replenishment condition for the chemical bath;
defining a unit of the replenishment condition;
establishing a pacing factor corresponding to a replenishment volume of a replenishment medium per unit of the replenishment condition; and
defining a replenishment threshold corresponding to the product of a predetermined number of the defined units of the replenishment condition and the pacing factor.
In one embodiment of this further aspect of the invention, there is provided the further step of counting elapsed units of the replenishment condition. Other embodiments include the steps of effecting a replenishment of the chemical bath when the replenishment threshold is reached, testing the chemical bath to determine the content of the chemical bath, and adjusting the quantum of the replenishment of the chemical bath in the step of effecting a replenishment of the chemical bath. The step of adjusting the quantum of the replenishment of the chemical bath is effected in accordance with the relationship:
PFxe2x80x2=PFxc3x97[1+(RA/T)xc3x97A],
which is described in greater detail hereinbelow. This embodiment may include the step of adjusting the replenishment of the chemical bath and includes the further step of varying the replenishment threshold. In still further embodiments of the invention, the step of adjusting the quantum of the replenishment of the chemical bath includes the further step of varying the replenishment volume of the replenishment medium per unit of the replenishment condition.
Replenishment
The replenisher aspect of the present invention is a combination of software, computer/controller hardware, and chemical dispensing hardware that is able simultaneously to:
Receive commands and send responses or status to a host computer.
Receive commands and send responses or status to a user keypad and display terminal.
Start, monitor, and stop multiple chemical deliveries independently to multiple destinations.
Some of the parameters monitored or tracked by the system are:
Chemical flow rate
Chemical usage, cumulative
Chemical supply status (OK, low, empty)
Pump status (on, off, disabled)
Pump calibration factors
The following are employed to achieve accurate, variable and verified delivery volumes:
flow rate is limited to an approximate, predetermined value;
flow volume is measured by summing pulses from a paddle wheel flow sensor in the flow path;
flow is stopped when the intended volume is delivered by means of a shutoff valve.
The advantages of this approach are: 1) By limiting flow rate, the flow sensor is kept in a linear and, more importantly, reproducible volume per pulse range, thereby ensuring a high degree of accuracy. 2) By summing pulses and stopping at the desired pulse count (or volume), a variable, predetermined amount may be delivered, this system being considerably simpler than a variable flow rate system. 3) By using a flow sensor in place of, for example, a volumetric metering pump, the volume delivered can be verified rather than assumed.
The foregoing, in combination with the flow rate limiting method shown below (FIGS. 16 and 17), is less costly than other mechanical methods to deliver a variable volume. The use of a pneumatic pump with a constant pressure air supply provides feedstock at a constant pressure to a restricting needle valve or orifice. This method achieves the advantages of low cost and mechanical simplicity. The method attains its best accuracy, an important feature of this method, when the pump is used at approximately 1% to 10% of its flow rate capacity. Chemical flow rates are monitored during delivery. Very low or stopped flow rates are used to detect and to provide alarm indications of empty chemical supply conditions. This is used in place of an xe2x80x9cemptyxe2x80x9d supply level detector, which may or may not indicate what actually is available to a pump. Moreover, the flow rate, the accumulated amount delivered since start of delivery, and the total amount delivered since reset or refill of feedstock, are reported during delivery.
Paced Replenishment
The paced replenishment system of the present invention refers to replenishment at a rate that is proportional to some event, hereinafter referred to as the replenishment condition. Suitable events that constitute the replenishment condition include elapsed time, ampere-hours (or coulombs), number of product loads, product surface area, line speed over time, etc. The method of the present invention replenishes process constituents as they actually are consumed. It also prevents depletion (or buildup in the case of decanting a by-product) and the associated time delay related to detection and correction.
As previously noted, precision replenishment is a critical aspect of the inventive system. In respective embodiments, replenishment is automatically initiated at the following replenishment conditions:
Based on analysis result
Based on amp-minutes
Based on production
Based on Process time
Based on elapsed time
Based on operator request
In one embodiment, the system permits the operator to set the replenishment delivery calculations, based on analysis result and amp-minute accumulation (or other replenishment condition listed above) for each parameter/chemical(s). Once these settings are established, the system will automatically adjust the replenishment amount based on amp-minutes by the analysis result(s) for that plating bath.
For this replenishment tuning feature to be functional, a communications link is provided between the plating tool and the controller of the inventive system. This link will inform the system of amp-minutes(amperage), by plating cell/bath, so that it can initiate replenishment based on, for example, an amp-minute target.
More specifically, replenishment of a chemical bath proceeds at a predetermined rate that may be based on historical experience with the particular operating bath. Alternatively, the existing replenishment rate in effect in a given system may be predetermined based on experience with similar or related chemical systems. In accordance with an embodiment of the invention, the rate of replenishment is carried out in small batches, or aliquots, of a user-defined volume at a frequency controlled by the time required for the pacing signal to reach the trip point. The trip point is a predetermined sum of paced unit(s), for example, 10.0 ampere-minutes or 3 product loads. The volume delivered after the trip point is reached is defined by the following relationship, which corresponds to the volume delivered on or after the real time paced units accumulate to equal or excess this paced units trip point:
Replenishment volume=PFxc3x97P
Where,
PF=Pacing factor, in units of replenishment volume per paced unit accumulated
P=Paced units accumulated of the replenishment condition
The paced units are continuously accumulated in real time. Also, the chemical bath is sampled periodically to determine whether the rate of replenishment is adequate to maintain the desired balance of chemical constituents. In situations where the result of the sampling indicates that the chemical bath is under-concentrated, as would be the case where too much H2O is added or decanted, or replenishment is delayed or inadequate, the volume of the next single delivery of the replenishment material is increased. Alternatively, the replenishment volume is maintained the same, but the subsequent replenishment is caused to occur sooner, essentially by retaining unused but accumulated paced units.
In a further embodiment of the invention, the replenishment ratio, i.e., the pacing factor, is adjusted in response to intermittent quantitative analyses. That is, the ratio of feedstock is replenished in proportion to the accumulated signal or pacing factor. Since the equipment of the present invention can perform accurate intermittent quantitative analyses on the content of the chemical bath, the results of such analyses are used intermittently to adjust the ratio of replenishment to accumulated pacing factor. In embodiments where the invention is employed for metal finishing chemical baths, the time interval for ratio adjustment, or tuning, ranges from one half hour to several hours, depending on the extent to which the process is dynamic, and its predictability.
Tuning is performed, in a highly advantageous embodiment of the invention, immediately after each analysis result is obtained. The adjustment, or tuning, is effected in accordance with the following equation:
PFxe2x80x2=PFxc3x97[1+(RA/T)xc3x97A]
Where,
PF=Current pacing factor, in units of replenishment volume per paced unit
PFxe2x80x2=New pacing factor
R=Replenishment amount calculated from current quantitative analysis result. This calculation is usually stoichiometric.
T=Total paced replenishment since last analysis result. This excludes any amounts replenished for other reasons, such as in response to an analysis or operator request.
A=Fractional adjustment rate, 0 less than Axe2x89xa61. A controls how fast the pacing factor is tuned. Processes which require a quick response and have high analytical certainty use a setting of A near 1.0. Processes which are less dynamic or have lower analytical certainty use a lower setting for A, such as less than 0.5.
In comparison to standard PID (Proportion, Integral, Derivative) control, the method of the present invention recovers from integral error (a constant offset) by replenishing the total amount necessary to return to the process control set point after each analysis. Integral error is intentionally not taken care of by the ongoing paced replenishment alone, is to avoid subsequent overshoot and correction after the set point is reached and to accomplish more immediate recovery.
Overshoot is corrected by pausing paced replenishment until a volume of delivery is bypassed (not delivered) equaling the calculated volume that would have caused the overshoot. The tuning equation is used as always, expect that the R term becomes negative. As is the case with integral error, this avoids subsequent undershoot and correction alter the set point is reached and to accomplishes a more immediate recovery.
In a specific illustrative embodiment of the invention, the implementation of the invention includes:
1. pacing signal conditioning to convert or amplify the signal to an acceptable range;
2. signal conversion to digital form;
3. signal integration, to produce a sum of the input over time;
4. comparison of the integrated signal against a trip point at which a small dose of replenishment is initiated; and
5. delivery of a present replenishment amount and reset of the signal integral to zero.
Chemical Concentration Control (Further Embodiment)
Tuning, in accordance with a further embodiment of the invention, is based on the following:
When an analysis result is obtained, the change in analytical reading since the last analysis is calculated. If result averaging is in effect, this same equation applies but the Current Reading is replaced with the average of the current and previous n readings and the Previous Reading is replaced with the average of the previous reading and its corresponding previous n readings.
Change in Analytical Reading=Current Readingxe2x88x92Previous Reading
Then, the extent to which replenishment lacked (xe2x88x92) or was over-delivered (+) to have no change in reading is calculated. The contribution of other, non-paced replenishments is also accounted for in the equation:
Paced Replenishment Error=Change in Analytical Readingxc3x97Analytical Replenishment Factorxe2x88x92Sum of Non-Paced Replenishments Since Last Analysis
where, xe2x80x9cAnalytical Replenishment Factorxe2x80x9d is the multiplier used to convert an analytical result to a replenishment quantity. It is expressed in replenishment units over analytical units, such as liters replenishment per gram/liter below target. The xe2x80x9cSum of Non-Paced Replenishments Since Last Analysisxe2x80x9d includes all replenishments that are not time or amp-minute based, such as the one in response to the previous analysis result or those done manually. A new replenishment factor is then calculated in accordance with the formula:
New Factor=Old Factorxe2x88x92Old Factorxc3x97(Tuning Rate/100)xc3x97Paced Replenishment Error/Sum of Paced Replenishments Since Last Analysis
where, xe2x80x9cTuning Ratexe2x80x9d is the rate of tuning, expressed as a percentage from 0 to 100.0. A typical operating value is 20.0. It depends on the analysis error, analysis frequency, and rate of process change. That is, the user will set it in proportion to (rate of change/analysis error/analysis frequency).
Another equation, derived for a two factor tuning method, affords the advantage of not xe2x80x9cgetting stuckxe2x80x9d if the factor reaches zero. It is first a calculation for xe2x80x9cIdeal Factor,xe2x80x9d which is the factor if all readings and data are perfectly accurate.
Total Chemical Consumed=xe2x88x92Change in Analytical Readingxc3x97Analytical Replenishment Factor+Sum of All Replenishments Since Last Analysis
Ideal Factor=Total Chemical Consumed Pacing Units Accumulated Since Last Analysis
or
Ideal Factor=(xe2x88x92Change in Analytical Readingxc3x97Analytical Replenishment Factor+Sum of All Replenishments Since Last Analysis)/Pacing Units Accumulated Since Last Analysis
and
New Factor=Old Factorxc3x97(1xe2x88x92Tuning Rate/100)+Ideal Factorxc3x97(Tuning Rate/100)
Note that with these equations tuning is skipped if the xe2x80x9cPacing Units Accumulated Since Last Analysisxe2x80x9d is zero.
Two Factor Tuning
When two different factors such as amp-minutes and time deplete the solution are to be considered, the factors must be determined algebraically since they usually deplete simultaneously but at different rates. The equations are most easily solved without the xe2x80x9cTuning Ratexe2x80x9d terms. These are subsequently added.
Paced Replenishment Error 1=Change in Analytical Reading Due to 1xc3x97Analytical Replenishment Factorxe2x88x92Sum of All Replenishments Since Last Analysis+Sum of Paced Replenishments 1
Change in Analytical Reading Due to 1=Paced Units 1xc3x97Ideal Pacing Factor 1 where, xe2x80x9cPaced Units 1xe2x80x9d is the sum of the paced units that were reported since the last analysis, such as amp-minutes. And where xe2x80x9cIdeal Pacing Factor 1xe2x80x9d is the actual, but unknown, conversion factor to convert from paced units to replenishment amount. This gives:
Paced Replenishment Error 1=Paced Units 1xc3x97Ideal Pacing Factor 1xc3x97Analytical Replenishment Factorxe2x88x92Sum of All Replenishments Since Last Analysis+Sum of Paced Replenishments 1
Paced Replenishment Error 2=Paced Units 2xc3x97Ideal Pacing Factor 2xc3x97Analytical Replenishment Factorxe2x88x92Sum of All Replenishments Since Last Analysis+Sum of Paced Replenishments 2
xe2x80x83Total Paced Replenishment Error=Change in Analytical Readingxc3x97Analytical Replenishment Factorxe2x88x92Sum of All Replenishments Since Last Analysis+Sum of Paced Replenishments 1+Sum of Paced Replenishments 2
or:
Total Paced Replenishment Error=Paced Replenishment Error 1+Paced Replenishment Error 2
To shorten the equations:
A=Total Paced Replenishment Error
B=Analytical Replenishment Factor
E1=Paced Units 1
E2=Paced Units 2
X1=Ideal Pacing Factor 1
X2=Ideal Pacing Factor 2
C=Sum of All Replenishments Since Last Analysis
D1=Sum of Paced Replenishments 1
D2=Sum of Paced Replenishments 2
F=Change in Analytical Reading
O=Analytical Replenishment Factor
Paced Replenishment Error 1=E1xc3x97X1xe2x88x92C+D1
Paced Replenishment Error 2=E2xc3x97X2xe2x88x92C+D2
Total Paced Replenishment Error=Fxc3x97Gxe2x88x92C+D1+D2
Since:
Total Paced Replenishment Error=Paced Replenishment Error 1+Paced Replenishment Error 2
then substituting gives:
Fxc3x97Gxe2x88x92C+D1+D2=E1xc3x97X1xe2x88x92C+D1+E2xc3x97X2xe2x88x92C+D2
Rearranging for X1 gives:
X1=(Fxc3x97Gxe2x88x92C+D1+D2+Cxe2x88x92D1xe2x88x92E2xc3x97X2+Cxe2x88x92D2)/E1
Combining terms gives:
X=(Fxc3x97G+Cxe2x88x92E2xc3x97X2)/E1
or:
xe2x80x83Ideal Pacing Factor 1=(Change in Analytical Readingxc3x97Analytical Replenishment Factor+Sum of All Replenishments Since Last Analysisxe2x88x92Paced Units 2xc3x97Ideal Pacing Factor 2)/Pacing Units 1
and
Ideal Pacing Factor 2=(Change in Analytical Readingxc3x97Analytical Replenishment Factor+Sum of All Replenishments Since Last Analysisxe2x88x92Paced Units 1xc3x97Ideal Pacing Factor 1)/Pacing Units 2
Since these are two equations with two unknowns, they must be solved using two sets of data, namely, using the current to previous pair as one set and the previous to previous-previous pair as another set. Matrix algebra should suffice for this. The above equation can be simplified if constant terms are combined:
X=K/E1xe2x88x92X2xc3x97E2/E1
and
X2=K/E2xe2x88x92X1xc3x97E1/E2
where,
K=Fxc3x97G+C
Visual Basic User Interface
The Visual Basic User Interface (the Manager program) should include the following features:
1. A text box for entering the rate of tuning for each factor. This is a percentage, expressed from 0 to 100.0. The default for this is 100.0, which should be set lower only if the rate of consumption in proportion to the pacing factor is inconsistent.
2. A check box for selecting whether to hold off paced replenishment so that the concentration can return to target if it is high. The default for this box is true.
3. A text box for entering the number of previous readings (0 to 10) to use in calculating corrective replenishment or hold off volume. The default value is two, which is set higher when needed to smooth out more analytical error. The text box caption should be, for example, xe2x80x9cUse average of current and previous results.xe2x80x9d
Level Control
Level control in chemical process solutions is challenging because of the variety of conditions that are encountered. There are consequently many methods of level sensing, each with its own strengths and vulnerabilities. Surface foam, for example does not present a problem to most radio frequency (RF) level sensors, but registers as liquid to an ultrasonic or acoustic-sensor. RF sensors, however, are inoperative when lightly coated or when in low conductivity solutions.
Durability (or reliability) is also a problem. The electronics associated with most sensors inherently have a limited temperature operating range beyond which the sensor can be destroyed. Another example is that maintenance becomes problematical when a solution coats or crystallizes on surfaces. Finally, space constraints often limit where a sensor can be installed. Usually, it is the sensor head (or electronics package) that causes these space problems. For example, above an open tank it is common for a hoist to be used to move material being processed in and out of the tank. This xe2x80x9cmaterial flowxe2x80x9d limits what space is available for locating equipment above the tank liquid surface.
The present system employs a pneumatic level sensing technique in order to solve or prevent the aforementioned problems. (See, FIGS. 16 and 17) In general, this technique uses 1) a pressure regulated air or gas source, 2) a precision orifice or needle valve to limit the gas flow rate, 3) a pressure switch or sensor to detect the pressure within the tube and 4) a length of tubing of material inert to the process solution which is immersed in the solution and which internally takes on the pressure of the liquid at the depth where it terminates.
The orifice restricts airflow such that the pressure to the right (downstream) of the orifice is limited to the pressure head of the liquid above the bubbling tube outlet. A change in level is detected by the change in gas pressure required to keep the gas and liquid in equilibrium at the tube outlet. After the level rises, the gas will build in pressure until it equals the liquid pressure at the outlet, after which it will vent (bubble) and remain at equilibrium.
In some embodiments of the invention, there are employed:
1. a low pressure gas, for example less than 2 psi, to supply the system. This limits the maximum possible pressure and thus prevents damage to the low range pressure switch or sensor should the tube outlet become blocked;
2. a fine orifice, for example 0.008 to 0.020 inch diameter. This slows gas flow, allowing it to assume a pressure equal to the immersed liquid head height. It also is sufficient to keep the inside of the tube free of chemical coating and thus prevent buildup. This is particularly beneficial in solutions which otherwise dry and cake at air-liquid junctions. Although the invention is not limited to these orifice sizes, these sizes we have chosen have worked well in a practicable embodiment.
3. oversized tubing. By using tubing much larger than required, for example xe2x85x9c inch diameter instead of xe2x85x9 a inch, all measurable pressure drop attributable to air flow is eliminated. This allows the pressure sensor and associated equipment to be placed remotely from the solution in a safe, convenient and/or centralized location. In a practical embodiment of the invention, up to one hundred feet of distance has been used with no loss in performance.
4. a tube or pipe section in contact with the solution can be further oversized, for example to xc2xd inch or even 1 inch diameter, so that plugging of the outlet such as by dried material is much less likely. While plugging of the outlet has not been a problem in the practical embodiment, this technique may be useful in certain solutions.
5. Where inert, higher cost material is required in contact with the solution, a connection may be provided to convert from one tubing of standard material, such as nylon, polyurethane, or polyethylene to an inert material, such as Teflon(copyright), prior to entering the solution. This also has the advantage of providing a convenient way to replace the immersed tube or pipe section should it become damaged or fouled.
6. By using two level sensors immersed at a fixed, known vertical distance apart, the pressure readings may be corrected for changes in solution density before converting the reading to level or volume. Of course, this method only applies to continuous analog level sensing, not discrete point level switching. The software used in conjunction with this level measurement method accomplishes the following:
1. xe2x80x9cDebouncingxe2x80x9d of the wave action in the tank. Since the tank solutions being measured undergo agitation, either intentionally or by work flow, the level is not constant, but is actually wavy. The software removes this xe2x80x9cnoisexe2x80x9d switch type level detection to give a consistent, useful reading. The method for doing this, however, is not just to create a large hysteresis (or deadband) in the switch, and thus lessen precision, but is to sum and average xe2x80x9chighxe2x80x9d and xe2x80x9clowxe2x80x9d (on and off) readings. Thus if over a five second period a total of eight high and two low readings are obtained, the level is calculated to be at the 80% of the switching range. This integer value is used to attain precise control within a narrow range. The programmer, for example, may set the refill to begin at 70% and end 80%.
2. A further improvement on this technique has been to use a weighted average where the most current readings have the most weight. The simplified equation for this is:
New average level=(((100xe2x88x92W)xc3x97Previous average level)+(Wxc3x97Current level reading ))/100,
where the Current level reading is either zero or one and xe2x80x9cWxe2x80x9d is the weight to give to the newest reading. A typical range for xe2x80x9cWxe2x80x9d is 5 to 20, depending on how quickly a change in tank level is to be responded to (higher xe2x80x9cWxe2x80x9d) versus how much dampening of wave action is desired (lower xe2x80x9cWxe2x80x9d). This weighting technique is applicable to both discrete and analog sensors.
3. With this approach, wave action can be used to confirm the functionality of target level sensor. Any reading between (but not including) 0% to 100% confirms that the switch is responding to level changes, such as caused by wave action. By starting filling when level is in the switching rangexe2x80x94a normal mode of operationxe2x80x94slight agitation in the tank can be used to confirm sensor functionality.
4. A user settable control also allows automatic overfill, if desired, so as to reduce switch and fill valve cycling and thus increase in mechanical component life span.
5. Where two level sensors are used, each one is also used to confirm the proper operation of the other. When installed at different levels, the lower sensor is used as the process or target level; the higher sensor is used as an alert or warning level. When arranged in this way, if the lower sensor reads anything less than 100%, the only valid reading for the higher sensor is 0%. It is only when the lower sensor reads 100% that the higher sensor may read more than this. Conditions outside of this are reported as errors to the operator and are interlocked in the software to prevent hazardous or overfill operations. (It is common in the industry to use two sensors where the signal from one is used to turn on a filling or emptying device and from the other to turn it off. Thus the second sensor cannot be used to back up the first because it must be employed in the level control operation. For protection or interlocks a third sensor is required.
6. As a further protection against failure, software timers are employed to stop filling and alert the operator if the level does not 1) measurably rise within a preset time or 2) reach target within a (longer) preset time. Automated filling is not allowed until after an operator initiated reset occurs or the level is restored to the target by some external means.
7. This creates a failsafe design, which means that failure of the sensor(s) does not create a further hazard. A false high sensor reading results in no filling action; a false low results in a timed out filling attempt. (The filling time limit is set equal to less than the time required to fill the tank from the sensor to the rim.)
Specific Copper Plating Embodiment
In a specific illustrative embodiment of the invention that is adapted specifically for a copper plating environment, the system is designed to eliminate the need for manual analysis and replenishment of the chemicals associated with the control parameters of the copper plating baths. The system of the present invention also provides automatic sensor calibration and internal system diagnostics maintain a high degree of reliability, repeatability, and throughput performance. In addition, efficient trouble shooting and reduced maintenance requirements are achieved.
In this embodiment, an automatic analyzer is provided for copper sulfate, sulfuric acid, hydrochloric acid and two organic agents/additives. In a highly advantageous embodiment, the analyzer automates titrametric procedures and delivers sharp, distinct end-points in approximately five to seven minutes. With time spent for sampling, purging, sample preparation, redundant analysis, cleanup and trend checking, is included, the overall cycle time is therefore approximately between twenty and thirty minutes.
More specifically, this embodiment of the invention achieves automatic,
The analyzer of the present invention will also automate cyclic voltammetric stripping for the analysis of the organic components, as well as provide indication of the total organic contamination of the plating solution. These analyses, when selected to be performed for a particular tank, are programmed to run concurrently with the analysis for the inorganic components. Within the method (titration or CVS or CPVS), analysis will occur in sequence.
Housing
The system of the present invention is, in a highly advantageous embodiment, housed in a fire retardant polypropylene cabinet with see-through front, hinged (locked) door. The system uses a pH electrode, an ORP electrode, a chloride-ion-specific electrode, and a cyclic voltammetric stripping unit to automate the necessary analytical procedures. This cabinet is equipped with leak detection and secondary containment and is designed to accept chemical samples from up to three (3) pressurized sample lines.
The cabinet also houses a manager system that is provided with a viewing screen for monitoring various forms of activity, a CPU shelf, a pull-out keyboard locking drawer, printer stand and electrical panel for a local control unit (LCU). The overall approximate size of this cabinet, in a practical embodiment, is 48xe2x80x3Wxc3x9772xe2x80x3Hxc3x9724xe2x80x3D. The analyzer is connected to the manager, in this embodiment, via a RS422 data transfer arrangement. The LCU is a combination of software, computer or controller hardware, signal conditioning modules, sensors and actuators. It is used to monitor, control and report a variety of physical parameters including temperature, level, conductivity, pH, voltage, current, pressure, flow, and other parameters that can be measured by a sensor. It is employed where continuous monitoring and/or immediate control response is required. Also, it condenses continuous sensor readings into maximum, average, and minimum values over specified time periods and reports them to a supervisory computer (or Manager) as such. This approach both improves local monitoring and control response and reduces the computing and communications burden on the supervisory computer.
Chemical Replenisher Storage and Handling Unit
The Chemical Replenishment, storage and handling unit is manufactured of fire retardant polypropylene and is designed, in a specific illustrative embodiment of the invention, to accept five xe2x80x9cNOW-PAKxe2x80x9d four-liter containers. This unit includes the following:
The packaging approach is designed for clean room type environments. A practical embodiment of the present design complies with ST-93, CE xe2x80x9cEssential,xe2x80x9d and UL electrical standards.
In other embodiments, the chemical replenishment, storage and handling unit, manufactured of fire retardant polypropylene, can optionally be designed to accept five xe2x80x9cNOW-PAKxe2x80x9d 200 liter containers. To accommodate these requirements, the system may include:
a manager/PC controller with G E M/SECS Host communications output;
a automatic chemical analyzer;
a modified, integrated, on-line CVS unit;
a chemical replenisher control unit with custom Now-Pak, 200 liter replenishment system; and
a Local Control Unit with tower light, and audible alarm control functions as well as interlock control and monitoring.
In a copper sulfate plating embodiment of the invention, certain problems may arise that need to be addressed and/or repaired. These problems and their respective corrections may be as follows:


A lighting device for attachment to a motor vehicle inside a housing 4. One or more light emitting diodes 9 which emit substantially white light are employed as lighting emitters. On account of the small amount of waste heat of the light-emitting diodes 9 the lighting device can be particularly easily integrated into existing subassemblies of the motor vehicle, in particular into the outside mirrors, inside mirror, trim strips and door handles, and can serve to illuminate the region around the vehicle or the interior of the vehicle.

The invention relates to a lighting device for motor vehicles which is electrical and attaches with a housing to the vehicle.
Lighting devices of this type are arranged in the interior and exterior regions of motor vehicles and serve as interior lighting, reading lamps and lamps which are arranged in the region of the doors and which illuminate the ground around the vehicle in darkness in order to enhance the safety and the comfort of the users of the vehicle in the process of entry. By means of these lighting devices which are known as such, fouled areas and, in certain circumstances, sources of danger located beneath the vehicle can be recognized more easily-in addition, particularly in a dark environment, the subjective well being of the users of the vehicle is enhanced by the illumination of the environment of the vehicle. During the process of parking in an unilluminated environment the exterior lighting can be utilized as a parking aid.
With the known lighting devices, in the vast majority of cases incandescent lamps and, relatively rarely, also gas discharge lamps are employed as electrical lighting means. These two types of lighting means have major disadvantages for the stated purpose of illuminating definite regions inside or outside a vehicle.
The principal disadvantage with the use of incandescent lamps is their very high incandescent-coil temperatures which are made necessary by the system for operation and the high thermal loads that occur as a result, concentrated in one place. In addition, the incandescent lamps themselves are relatively large and offer acceptable light efficiency in operation only when they are installed together with an appropriate reflector. The high thermal losses, the size of the incandescent lamps and the use of reflectors give rise to a mi m size of such lighting devices, which cannot be reduced. This minimum size renders difficult the integration of this lighting device into subassemblies that are present on the vehicle, such as, for instance, the outside mirror, the inside rear-view mirror, vehicle sheets (panels), bumpers, trim strips, covers, consoles, shelves, glove compartments and ashtrays.
For this reason, in many cases the lighting devices have to be arranged in places that are unfavorable for the emission of light, since only in such places is the requisite space available for mounting of the lighting device. Since the size proportions are different in every vehicle, no universally applicable lighting devices can be employed that are economical to manufacture on an industrial scale, but rather a vehicle-specific lighting device has to be developed and manufactured for each type of vehicle overall, the creative scope as regards the design of lighting devices of this type is severely limited.
By virtue of the thermal losses of incandescent lamps which occur concentrated in one place, temperature problems arise in the region of the mounting location of the lighting device. As a result of the waste heat that arises, the materials of the surrounding subassemblies are very severely loaded thermally. In order to counteract damage to these materials, use is made of expensive, temperature resistant materials, and elaborate measures have to be provided for the dissipation of heat. Since even these measures would not be sufficient in the case of continuous loading, the maximum amount of waste heat has to be limited, to which end timing devices and/or thermal protection devices have to be provided, in order to switch off the lighting prior to the overheating of components. Besides, after the maximum thermal load has been attained, a long recovery interval is required with a view to cooling the components.
On account of the high temperature in the lighting coil of incandescent lamps the latter are susceptible to shock and vibration, and the service life of incandescent lamps lies distinctly below the service life of the vehicle. The lighting devices, particularly where use is made of elaborate optical systems, therefore have to be designed in such a way that the incandescent lamp can be exchanged. Since the lighting device has to be opened each time the incandescent lamp is exchanged, in the case of lighting devices arranged in the exterior region of the motor vehicle special means have to be provided for sealing. In addition, a lighting device that is capable of being disassembled gives rise to ledges or gaps in the surface of the subassemblies into which the lighting device is integrated, which can lead to wind noises or to vibration problems.
The spatial extent of the incandescent coil of incandescent lamps, together with the large exit aperture of the reflector to be used, results in a large divergence angle when light is emitted from the lighting device. A large divergence angle makes it difficult to exert influence on the beam path and hence to exercise deliberate control of the lighting characteristic, particularly also with regard to undesirable scattered light. For this reason the irradiated fields of illumination can only be adapted with difficulty to the optimal requirements of the lighting task by influencing the lighting characteristic. Optimization of the luminous-intensity distribution is also generally impossible for this reason, since, as a rule, only one incandescent lamp is used by way of light source. If extreme demands are nevertheless made as regards the shape of the luminous-intensity distribution, elaborate and expensive optical systems have to be employed, for instance special reflectors or asymmetric, nested Fresnel lens systems. The development and manufacture of such systems is time-consuming and expensive. Through the use of gas-discharge lamps only the problems caused by the thermal losses of incandescent lamps are neutralized. On the other hand, gas-discharge lamps require a still larger space for installation, and their lighting characteristic can barely be influenced, even through the use of special optical systems.
It is therefore the object of the present invention to create a lighting device that is fully capable of performing the function of the known lighting devices and that, at the same time, has a small minimum size, generates little waste heat, has a long service life which exceeds the service life of the vehicle, and has a lighting characteristic that can be well controlled. This object is achieved by means of a lighting device with a housing attachable to the vehicle and a light emitting diode positioned in the housing and emitting substantially white light.
The use of light emitting diodes for performing lighting functions is known in principle. Light-emitting diodes are relatively small that is, they generally have a diameter in the range from O,.S to 10 mmxe2x80x94and therefore require a relatively small minimum size, have a high efficiency, generate only little waste heat and have a long service life which exceeds the service life of the vehicle. The lighting characteristic of light-emitting diodes can be well controlled by appropriate beam-deflecting devices and/or appropriate lens systems.
One disadvantage of the light-emitting diodes known hitherto was that only monochromatic lightxe2x80x94that is, light of a single colorxe2x80x94of relatively low luminous intensity could be generated with them. This weak, colored light could not be used for performing most of the lighting tasks in the vehicle. As a result of the further development of light-emitting diodes it has been possible since only recently to manufacture light-emitting diodes that emit white light of relatively high luminous intensity and that are therefore able to replace the incandescent lamp or fluorescent tube by way of lighting means in lighting devices of motor vehicles. These novel light-emitting diodes are ready to come onto the market and have been cleared for use in motor vehicles.
As a matter of principle, light-emitting diodes having arbitrary available luminous intensity can be employed, whereby the luminous intensity of the light-emitting diodes and the number of light-emitting diodes to be employed have to be matched to the particular lighting task, in particular to the distance of the object to be illuminated. In this connection the light-emitting diodes should, as a rule, exhibit an emission angle that is as small as possible, in order to generate little scattered light. Light-emitting diodes are available that comprise an integrated lens and have an emission angle in the range from 10 to 30xc2x0.
The color of the white light that is capable of being generated by the light-emitting diodes is conditioned by the structural design and cannot be altered. In case this light color is not optimally suited for performing a definite lighting task, the lighting device should comprise at least one light-emitting diode that emits monochromatic light that is, colored light. The monochromatic and white light of the various light-emitting diodes mix on the field of illumination, as a result of which the light color can be optimally adapted to requirements by means of an appropriate mixing ratio.
In many cases the luminous intensity of one light-emitting diode alone is not sufficient for illuminating a sufficiently large field of illumination with adequate luminous intensity. In these cases several light-emitting diodes have to be combined in the lighting device, in order to add the luminous intensities of the individual light emitting diodes on the field of illumination.
Owing to the structural design, the individual light emitting diodes in the lighting device have to be arranged side by side. Since the light-emitting diodes generate a cone of light which spreads out in substantially linear manner along its beam axis, several circles of illumination located along side one another arise on the field of illumination as a result of the several light-emitting diodes. Accordingly, through the simple addition of further light emitting diodes, the size of the field of illumination can be enlarged, but an increase in the luminous intensity at a definite point of the field of illumination is not possible in this way.
If the light emitted from the lighting device is to be concentrated at one or more definite points in order to change the lighting characteristic, at least two light emitting diodes with beam axes extending in non-parallel manner in relation to one another may be arranged to this end in the lighting device. The relative arrangement of the light emitting diodes should be chosen in such a way that the circles of light overlap on the field of illumination so as to correspond to the desired lighting characteristic.
Although by virtue of the arrangement of the light-emitting diodes in the lighting device the lighting characteristic can be varied by means of differing emission angles, to this end an elaborate carrier body for the light-emitting diodes is necessary which provides for the appropriately aligned relative arrangement. In particular, the arrangement of light-emitting diodes on a printed circuit board is then not possible, since the light-emitting diodes on a card module of this type all exhibit the same beam axis path perpendicular to the printed board. If the lighting characteristic is to be influenced in these cases, then a lens system arranged in front of the light-emitting diodes can be arranged in the beam path of the light emitted from the individual light-emitting diodes. The lens system deflects the light beams in a manner corresponding to the desired lighting characteristic. The arrangement and configuration of the individual lenses in the lens system should be matched to the desired lighting characteristic.
If a field of illumination of particularly differentiated form is necessary, both concepts can be combined with one another with a view to influencing the lighting characteristic. That is, on the one hand the lighting device scatters the light through a lens system and the individual light-emitting diodes have a specially aligned beam axis.
It is particularly economical in manufacture to combine the individual light-emitting diodes of a lighting device in a manner known as such on a printed circuit board or conductor foil (pcb""s) so as to form an LED module. With the use of a printed circuit board a two-dimensional distribution of the light-emitting diodes is possible, with the use of conductor foil a three-dimensional distribution of the light-emitting diodes in the lighting device is possible. Via the printed circuit board or conductor foil the light-emitting diodes can be provided with current centrally and the LED module can be simply mounted in the form of a prefabricated subassembly in a housing. As a matter of principle, the electronics for driving the light-emitting diodes may be arranged at any place in the vehicle, even at a place remote from the light-emitting diodes, for instance by integration into an on-board computer. In an embodiment worthy of preference, the electrical circuits for driving the light-emitting diodes that is, the necessary electrical components and electrical conducting paths, can be combined together with the light emitting diodes on a printed circuit board or conductor foil so as to form an LED module. This integration reduces the effort expended on cabling and mounting. The card modules can be manufactured economically on an industrial scale in a manner known as such.
If the lighting device is employed in the exterior region of the motor vehicle, measures have to be taken in order to rule out contact of the LED module with water. Penetrating moisture can give rise to fault currents and short-circuits and hence lead to malfunctions of the electrical components and damage thereto. The LED module should therefore preferably be constructed so as to be protected against water, in order to prevent contact of penetrating moisture with the electrical components. As a result of the water protected construction of the appropriate regions of the LED module an elaborate water-tight seal of the entire housing can be dispensed with. The moisture protection can be achieved in particularly simple and economical if the LED module is cast at least zonally into a water resistant material, for instance a resin. When designing the resin mantle, care should be taken to ensure that sufficient dissipation of heat from the LED module is possible. The light-emitting diodes themselves should not be cast in resin, since excessive light losses would be caused as a result. The unprotected regions of the LED module, for instance the side of a printed circuit board on which the light-emitting diodes are arranged, should be protected against moisture by appropriately different sealing measures.
Since the service life of the light-emitting diodes exceeds the service life of the motor vehicle, under normal circumstances the exchange of light emitting diodes during the service life of the motor vehicle is not necessary. Therefore it is particularly favorable to connect the light-emitting diode or the LED module to the housing permanently, for the permanent connection between light emitting diode or LED module and the housing can be manufactured in particularly economical manner, for instance by bonding the components with adhesive, and is particularly vibration-proof and shock-proof. If a light emitting diode fails during the service life of the vehicle, then in the case of single-part housings the entire housing has to be exchanged, in the case of multi-part housings the housing part that is permanently connected to the light-emitting diode or the LED module has to be exchanged. Although this makes the exchange of the light-emitting diodes more expensive, on account of the intrinsically high life expectancy of the light-emitting diodes it occurs very rarely.
In principle it is sufficient if the light-emitting diodes are arranged on the outside of the housing of the lighting device and the generated light can be emitted towards the desired field of illumination. However, in this case the light-emitting diodes are exposed to all external influences, in particular to mechanical damage and atmospheric influences. In order to protect the light-emitting diodes against these influences it is advantageous if a transparent cover plate is arranged in the housing in the beam path of the light-emitting diodes. In other words, the light-emitting diodes are accommodated in encapsulated manner between cover plate and housing. The light generated can pass unhindered through the transparent material of the plate, and unfavorable mechanical and atmospheric influences are kept away from the light emitting diodes. The plate should therefore have sufficient mechanical strength and be connected to the housing so as to be as watertight as possible. If the lighting characteristic of the lighting device is to be influenced by the arrangement of a lens system in front of the light-emitting diodes, this can be accomplished in particularly economical manner if the necessary lenses are incorporated into the transparent cover plate in front of the light-emitting diodes. This can be effected by means of an appropriate ground surface of the cover plate or by the arrangement of lens-type regions of thicker material in the cover plate. It is particularly favorable to form the regions located in each instance opposite a light-emitting diode as lenses on the side of the cover plate facing the light-emitting diodes. Hence the beam path of the individual light-emitting diodes can be selectively controlled, since for each light-emitting diode a lens is provided with which the light beam can be deflected, and the smooth outside of the cover plate can be connected in substantially gap-free manner to the outside of the housing, so that no dirt can get caught in the transition region and no undesirable wind noises arise. In addition, the lenses on the inside of the cover plate are protected against damaging mechanical influences.
The cover plate may be manufactured from any transparent material and, accordingly, in particular also from glass. However, glass has the disadvantage that it in relatively brittle and therefore breaks easily and the provision of lenses in the glass, for instance by means of an appropriate ground surface, is relatively elaborate. In an embodiment worthy of preference, the cover plate should therefore be manufactured from a transparent plastic. Plastic is light, has a sufficiently high mechanical strength and furthermore is weather-resistant. A cost advantage results from this, namely that the requisite lens system can be manufactured very simply by appropriate modification of the shape of the plastic cover plate. To this end-lens-shaped elevations merely have to be provided on one or both sides of the cover plate. To achieve this, the negative shape of these lens-shaped elevations merely has to be incorporated into an injection mould. As a result, the tool costs increase by a small amount, but the actual manufacturing costs of a cover plate with lenses made of plastic are no higher than those of a cover plate with no lens.
In connection with the shaping of the lenses it is advantageous to provide smooth lensesxe2x80x94that is, lenses having a smooth lens surface. Although lenses with surface structure, for example Fresnel lenses, are also conceivable, the sure structure reduces the light efficiency of the lighting device.
The cover plate is inserted into the housing in the region above the light-emitting diodes and is secured. In this regard a secure seating of the cover plate has to be guaranteed, in order that the latter does not get lost after a relatively long period. In addition to this, the light-emitting diodes must be protected as far as possible against moisture and dirt, on account of which the gap between cover plate and housing should be sealed as tightly as possible. This can be achieved, for instance, by the cover plate being secured into the housing with adhesive.
It is more economical if the cover plate and the housing are manufactured jointly in a multi-part injection-molding process. In this case the housing made of simple plastic and the cover plate made of transparent plastic are manufactured simultaneously in a common injection mold. In the process, the transparent plastic of the cover plate connects to the plastic of the housing in an interface, so that the cover plate becomes an integral constituent of the housing. With this design the light-emitting diodes are securely protected against moisture and dirt, since there is material closure between cover plate and housing. In case, for instance, the two plastics for cover plate and housing are not compatible with one another and therefore cannot be processed jointly in an injection mould, it in also possible of course to manufacture the two components separately and to connect them to one another by means of a clip connection or such like.
Since the properties of light-emitting diodes, in particular the current-carrying capacity and the luminous intensity emitted, are temperature-dependent, the current supply of the light-emitting diodes should be effected in a manner known as such via a non-linear resistance network or a device for pulse-width modulation. In particular, by means of a pulse-width modulation of the current it is possible for the necessary temperature compensation of the current characteristic to be implemented simply and, in addition, for smooth switching of the light-emitting diodes on and off to be achieved with a view to enhancing comfort.
Since fluctuations in the operating voltage in the on-board supply system of a motor vehicle may occur which can damage the light-emitting diodes, measures should be taken to protect the light-emitting diodes against overvoltages. For example, at least one protective diode should be connected in series to the light-emitting diodes in order to protect them against polarity reversal. Of course, other protective measures are also conceivable, but protective diodes enable particularly low peak reverse voltages.
Since light-emitting diodes also generate a certain degree of waste heat, the temperature in the lighting device, particularly in the case of continuous operation of the lighting device, can rise to an impermissible high level. In order to be able to rule out damage to the components as a result of excessive temperature loading it is advantageous to monitor the temperature in or on the lighting device with a temperature sensor. The output signal of this temperature sensor can then be relayed to the control system of the current supply of the light emitting diode, and the current supply can be controlled as a function of the temperature in the lighting device as measured by a temperature sensor. In this connection the control system either may confine itself to switching off the current supply in the event of a reference temperature being exceeded or may ease off the current supply in proportion to the temperature.
In order to be able to utilize the light emitted by the light-emitting diodes optimally it is advantageous to provide light-guiding elements on the light-emitting diodes that concentrate the generated light in one direction. One variant of such a light-guiding element arises if the light-emitting diode is surrounded by a pipe-like tube. The light is reflected in the tube and is able to emerge only at the opening of the tube. Light-guiding elements are also conceivable that are arranged at least on one side of the light-emitting diode. By means of these one-sided light guiding elements, a shadow is generated on one side of the light-emitting diodes and the entire amount of light is emitted in the other direction.
Of course, it is possible to configure a lighting device of the proposed type as an individual subassemblyxe2x80x94ie, with its own housingxe2x80x94and to secure it in or on the vehicle. However, it is visually more appealing and more economical to design the housing as part of an existing subassembly. In other words, this means that the lighting device is integrated into another subassembly, and a multi-function subassembly with a common housing is formed in this way.
In principle, many subassemblies of a motor vehicle are conceivable into which a lighting device of the proposed type could be usefully integrated. Subassemblies that may be mentioned are, in particular, bumpers, sunroof operating modules, luggage-compartment covers, engine-compartment covers, glove compartments, ashtrays, vehicle keys, storage compartments, center consoles, seats and such like. This holds true all the more, since no lighting devices were able to be integrated into many of these subassemblies on account of the lack of construction space or the inadequate dissipation of waste heat. It is particularly favorable if the housing of the lighting device is formed as part of an inside rear-view mirror, as a result of which the lighting device becomes an integral constituent of the inside rear-view mirror. By virtue of the positioning of the inside rear-view mirror in the upper region of the passenger compartment the lighting device can serve in particular as a reading lamp and/or for illuminating the interior. Since the light-emitting diodes require only a small construction-space and give off little waste heat, the inside rear-view mirror does not have to be changed substantially in its external slender shape. For this reason, reshaping can largely be dispensed with. If a lighting device according to the invention is arranged in the interior of the vehicle, said lighting device may, given appropriate matching of the lighting characteristic, also continue to burn during vehicle operation and thereby illuminate, selectively and with little glare, partial regions of the interior of the vehicle during the journey, for instance the gear-shift lever or shelf surfaces.
Also, a plurality of white light emitting diodes of this present invention can be positioned to radiate down from the lower portion of the interior rearview mirror housing to function as a map/reading light for illuminating the lap region of occupants seated in the front driver seat and/or front passenger seat. A cluster of at least two, and preferably at least four, white light emitting LEDs can be positioned at the driver side of the interior mirror housing and can be turned on at will by the driver via a switch. Likewise, a corresponding cluster of LEDs can be provided at the passenger side of the interior rearview mirror housing. Such a multi-LED cluster can form a light module. Alternatively, a light module comprising a cluster of white light emitting LEDs can be positioned to radiate from a pod attached to a rearview mirror assembly mount. It is also advantageous to form the housing of the lighting device as part of a trim strip. Trim strips of this type with integrated lighting device may then be arranged in the door region of the motor vehicle and illuminate the region of the road below the doors during the process of entry. Implementation of a lighting device in the trim strip with one or more incandescent lamps would not be possible, on account of the requisite construction space and the large amounts of waste heat. On the other hand, a narrow elongated printed board with a plurality of light-emitting diodes arranged thereon can be integrated very well into the narrow structure of a trim strip.
On account of their solid geometry the door handles of the vehicle are likewise very well suited for the integration of a linear arrangement of light-emitting diodes. To be considered in particular in this connection are the handles on the driver""s side, on the front passenger""s side and on the rear side. The lighting device integrated into the door handles may either be employed for illuminating the surrounding region outside the respective door and/or serve as an orientation aid making it easier for the users of the vehicle to find the door handles.
Lighting devices that are integrated into the outside rearview mirror serve the same purpose of illuminating the entry region outside the doors. A design that is worthy of preference is therefore to form the housing of the lighting device as part of an outside rear-view mirror. The small structural design of the individual light-emitting diodes makes it possible to position them optimally in the outside rear-view mirror for the purpose of performing the lighting task. This means that the light-emitting diodes may be arranged very far out, close to the outer end of the outside rear-view mirror, something which is not possible in the case of lighting devices with an incandescent lamp, since only very little construction space is available in this region of the outside rear-view mirror. In addition, the placement of the lighting device at the outer end of the outside rear-view mirror makes possible the illumination of the part of the entry region that is already situated below the floor of the vehicle.
Vehicle types of particularly high quality are equipped with outside rear-view mirror that are capable of being folded away. If, for example, the vehicle is being parked, the outside rear-view mirror can be swivelled towards the vehicle body by means of an electrical fold-away drive, in order to prevent damage. As a result, the outside rear-view mirror can occupy two different positions. If the housing of the lighting device according to the invention is formed as part of the outside rear-view mirror, a different path of the light beam arises as a result of the outside rearview mirror being folded away. The consequence of this can be that the lighting device in the first position of the outside rear-view mirror illuminates the region of the road outside the doors, as desired, and in the second position it irradiates only the vehicle body.
In the case where the lighting device according to the invention is incorporated into an outside rear-view mirror that is capable of being folded away, the lighting device should for this reason preferably comprise at least two groups of light-emitting diodes, the current supply of the individual groups of light-emitting diodes being capable of being switched as a function of the position of the outside rear-view mirror. In the extreme case, each of the groups of light-emitting diodes may also consist of only one individual light-emitting diode.
Since the proposed lighting device is not desired by all prospective buyers of a vehicle type at a correspondingly higher price, it is conceivable for only some of the vehicles of one type that have been delivered to be provided with such lighting devices as special equipment. If the lighting device is not fitted in all vehicles of one type but only as special equipment, depending on the wishes of the customer, the lighting device should take the form of a removable part of a vehicle assembly, in particular as a cover ring or covering cap of an outside rear-view mirror. By this means all vehicles of the same type could be equipped with, in principle, the same vehicle subassembly, for instance an outside rear-view mirror, and the modification with respect to the special equipment would be possible by order-related exchange of the removable part of this vehicle subassembly, for instance the cover ring or the covering cap of an outside rear-view mirror. By virtue of this measure, the multiplicity of parts in connection with the mounting of the motor vehicle could be diminished and the associated costs could be lowered.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.


The present invention relates to an identification element having an integrated circuit and an antenna coil connected to the integrated circuit.

This invention relates to an identification element having an integrated circuit and an antenna coil connected to the integrated circuit(RFID transponder)
The advantage of RFID transponders compared to the bar-codes predominantly used in particular in the goods marking sector is that they permit a direct exchange of information, meaning that no visual contact is needed between the interrogating device and the transponder for the information transfer. Unlike bar-codes, furthermore, it is an easy matter with RFID transponders to change their information content directly as and when required.
It will be understood, of course, that RFID transponders may find application in the most diverse areas, particularly in the fields of production, further processing and handling of goods as well as in the security sector. Examples include the identification marking of people and animals, the identification marking of baggage and packages, particularly at airports and post offices, and the identification marking of vehicles during their production or in multistory car parking garages.
The disadvantage of the known RFID transponders compared to bar-codes is the immense difference in price between the two elements. This is also the reason why the use of RFID transponders in the sales sector has been restricted so far to fringe areas. In particular there has been no interest to date in using RFID transponders to present price information or other data when selling mass products in department stores and warehouses, considering that an RFID transponder costs in the region of DM 10. This naturally makes their use as disposable identification markers completely out of the question.
RFID transponders are constructed as either passive or active elements. If the RFID transponder is used as an active element, the housing enclosing the integrated circuit contains an additional energy source usually in the form of a battery. RFID transponders are able to operate in the most diverse frequency ranges, for example, in the low frequency range at 125 kHz, in the medium frequency range at 13.56 MHz, or in the microwave range at typically 2.45 GHz. The present invention relates preferablyxe2x80x94but by no means exclusivelyxe2x80x94to passive transponders operating in the medium frequency range.
A data carrier with an integrated circuit is known in the art from European Patent EP 0 682 321 A2. The data carrier disclosed there is comprised of a card body and an integrated circuit connected electrically via contact elements to at least one coil composed of one or several layers. The elements combine to form a resonant circuit which operates at a predetermined resonant frequency. The purpose of the coil is to supply energy and/or to exchange the data of the integrated circuit with external devices. Circuit and contact elements are each constructed as a separate module.
The manufacturing cost of this known configuration of a transponder is so high that it is only suitable for use on up-market products. It is completely unsuited for use on mass products.
A method of bonding an integrated circuit to a resonant circuit mounted on a flexible substrate and a corresponding transponder is described in European Patent EP 0 821 406 A1. The resonant circuit disclosed is formed of two electrically conductive patterns arranged on either side of the flexible substrate. The resonant circuit has a certain inductance and a certain capacitance. To ensure a reliable bond between the integrated circuit and the resonant circuit, the bonding area on the flexible substrate is cleaned. Then the integrated circuit is connected to the resonant circuit by a technique referred to as wire bonding which is known from semiconductor technology. To prevent the bond from being destroyed by external impact, a protective coating is applied to the integrated circuit and the bonding area.
A disadvantage of this known method and known transponder is the relatively high cost for the individual parts and for the manufacture, considering that it is absolutely necessary, following bonding the integrated circuit to the resonant circuit, to apply a protective coating to the circuit and the bonding area. Typically, transponders are integrated into labels. Because in the area of the chip the transponder is substantially thicker than in the remaining areas, this presents major printing problems using, for example, a thermal printer for printing labels. Moreover, the conducting patterns forming the resonant circuit are applied to the substrate by etching. Etching is a relatively expensive process which, in addition, poses a severe environmental pollution problem.
It is an object of the present invention to provide an economically priced and reliably operating identification element.
This object is accomplished in that the antenna coil is comprised of a lower conducting track and an upper conducting track, that each track includes a plurality of turns, that the two tracks are arranged on either side of a dielectric layer, and that the relative position of the two tracks is such that they overlap substantially only in one or in two selected areas.
The advantages of the present invention reside in that the inductance of the antenna coil is relatively high as a result of the high number of turns of the two tracks. In particular, the inductance can be dimensioned such that, with a predetermined interrogation field in a predetermined space, the output voltage is sufficient to activate, that is, operate the integrated circuit. Furthermore, the feature involving overlapping of the two tracks essentially only at their inner and/or outer ends produces the effect that these areas make the major contribution to the capacitance of the antenna coil, while the contributions made by the remaining areas of track overlap (that is, the areas in which the tracks intersect) are vanishingly small. This makes it possible to obtain a higher inductance and hence again a higher induced voltage for operating the integrated circuit at the predetermined excitation frequency of the antenna coil.
In an advantageous aspect of the present invention, provision is made for the two antenna coils to be electrically interconnected in one of the two areas of track overlap, preferably in the outer area of track overlap.
In an advantageous further feature of the identification element of the present invention, provision is made for the integrated circuit to be a non-encapsulated chip. Obviously, this presents an extremely economical solution. In cases where the identification element is integrated into a label, printing as by a thermal printer is in addition substantially facilitated because a non-encapsulated transponder is substantially thinner than an encapsulated transponder.
Preferably, the conducting tracks are parts which are die-stamped from a metal foil material. A very low-cost method of manufacturing resonant labels is known in the art from European Patent EP 0 655 705 A1. The manufacturing method disclosed in this patent can be employed in the manufacture of the antenna coil.
According to an advantageous aspect of the solution of the present invention, it is proposed using a dielectric adhesive for the dielectric layer. This aspect is equally described in the European Publication referred to above.
The operating voltage of the integrated circuit, meaning the non-encapsulated chip, is of the order of 2 volts. In an advantageous aspect of the identification element of the present invention, provision is made for the number of turns of the tracks, which number is proportional to the inductance of the antenna coil and hence to the induced voltage, and for the size of the area of track overlap to be selected such that the output voltage of the antenna coil is in the voltage range with the predetermined interrogation field in a predetermined space.
To compensate for manufacturing tolerances, an advantageous embodiment of the identification element of the present invention provides for the antenna coil, following manufacture, to be tunable to the desired resonant frequency by the application of heat and pressure in the selected area or the selected areas. Preferably, tuning is performed by adjusting the distance between the two tracks in the area of track overlap by means of a heatable ram in such fashion that the antenna coil supplies the resonant frequency required for activation of the integrated circuit. The possibility also exists for such fine tuning to take place at a time when the integrated circuit is already bonded to the antenna coil.
According to a preferred embodiment of the identification element of the present invention, the antenna coil and the integrated circuit are interconnected through an electrically conducting adhesive bond. The adhesive bond used is one of the isotropic or anisotropic adhesive bonds well known from the field of semiconductor production. This is a very low-cost bonding method. In addition, it is readily applicable to the non-encapsulated chips utilized and the antenna coil described, which is fabricated from die-stamped tracks, and is hence eminently suitable.
In an advantageous aspect of the identification element of the present invention, the two conducting tracks of the antenna coil are of essentially like dimensions, and the conducting tracks are wound in opposing directions.
Furthermore, the end of the outer turn and the end of the inner turn of at least one of the two tracks preferably has a greater width than the balance of the track areas. As mentioned previously, the selected areas of track overlap lie in these inner and/or outer ends of the antenna coil. Because these areas are wider than the remaining track areas, a concentration of capacitance occurs in the corresponding area of track overlap. In the proximity of the overlap area, the chip, that is, the integrated circuit, is connected with the antenna coil. A concentrated total capacitance is substantially more favorable than a total capacitance presenting itself as the sum of a plurality of individual capacitances, because the total capacitance and hence the energy for operating the integrated circuit can thus be easily focused at the point where it is needed, that is, in the proximity of the chip.
In accordance with an advantageous embodiment of the identification element of the present invention, the transponder, that is, the chip, is located between the two inner turns of the two tracks in the area of an axis of symmetry of the identification element. This arrangement is of great advantage in particular in conjunction with the further feature of the identification element subsequently described. This further feature makes provision for two webs of a dielectric foil between the two conducting tracks and outside the area in which the chip is disposed. This foil increases the relative distance of the two conducting tracks, thus preventing a short circuit from occurring in the areas of overlap of the two conducting tracks which would deactivate the antenna coil. The dielectric foil is preferably made of polyester.
The present invention will be explained in more detail in the following with reference to the accompanying drawings.

Abstract: The antenna coil comprises a lower conducting track and an upper conducting track. Each track includes a plurality of turns, with the two tracks being arranged on either side of a dielectric layer. The relative position of the two tracks is such that they overlap substantially only in one selected area or in two selected areas.


A method and composition are provided for inducing or enhancing chondrogenesis in vivo or in vitro. The method is performed by exposing the cells in vitro or in vivo to an extracellular matrix comprising of type I collagen, type II collagen or a mixture of type I collagen or type II collagen and hyaluronate and further containing GDF-5.

The limited capacity of articular cartilage to regenerate represents a major obstacle in the management of degenerative and traumatic joint injuries. The maintenance of a functional joint surface requires that articular chondrocytes respond to extracellular signals that are generated from growth and differentiation factors, mechanical stimuli, and interactions with specific components of the extracellular matrix. The invention is directed to an extracellular matrix of type I collagen, type II collagen, type I collagen plus hyaluronate, or type II collagen plus hyaluronate, and differentiation factor-5 (GDF-5), a member of the bone morphogenetic protein (BMP) family that is involved in joint development on the chondrogenic activity of growth.
Coordinated function of many cell types is regulated by integration of extracellular signal derived from soluble factors inducing growth factors and insoluble molecules such as extracellular matrix (ECM). The skeletal elements of the vertebrate limb are derived during embryonic development from mesenchymal cells, which condense and initiate a differentiation program that result in cartilage and bone. Bone morphogenetic proteins may play a crucial role in mesenchymal condensations in skeletal patterning, including the process of joint formation. This is based upon in situ hybridization and immunostaining showing that GDF-5 is predominantly found at the stage of precartilaginous mesenchymal condensation and throughout the cartilaginous cores of the developing long bone; and null mutation in GDF-5 (frameshift mutation at the mouse brachypodism locus) resulting in disruption of the formation of approximately 30% of the joints in the limb. This includes the complete absence of joint development between the proximal and medial phalanges in the forefeet and hindfeet. Further evidence of the role of GDF-5 in regulating the cellular condensation required for chondrogenesis and joint formation comes from null mutation of noggin gene which is a known antagonist of bone morphogenetic protein function. While, in mice lacking noggin, cartilage condensation initiated, the process of joint formation failed as judged by the absence of GDF-5 expression.
Despite the importance of joint formation in skeletal patterning and human disease, relatively little is known about the molecular mechanisms that control where and when a joint will form. In the limb, joints typically arise by the splitting of larger skeletal precursors, rather than by collision or apposition of separate elements. This process takes place through a series of steps including: 1) initial formation of specialized regions of high density that extend in transverse stripes across developing cartilage element; 2) programmed cell death and changes in matrix production in the center of the interzone, creating a three layer structure; 3) differentiation of articular cartilage at the two edges of the interzone; and 4) accumulation of fluid-filled spaces that coalesce to make a gap between opposing skeletal elements. Expression of GDF-5 is initiated in the region of joint development 24-36 hours before the morphological appearance of the interzone. The expression continues for at least 2-3 days at a particular site, and is still evident at the three-layered interzone stage of joint development. The expression level of GDF-5 then decreases at later stages of joint formation. In vitro biological and biochemical analyses of recombinant hGDF-5 suggest that the primary physiological role of GDF-5 may be restricted to early stages of chondrogenesis of mesenchymal progenitor cells. This is based on a showing that: 1) GDF-5 stimulates mesenchymal aggregation and chondrogenesis in rat limb bud cells; 2) GDF-5 fails to stimulate alkaline phosphatase activity measured utilizing well differentiated osteoblastic cell type MC3T3-E1 cells; 3) GDF-5 stimulates alkaline phosphatase activity in rat osteoprogenitor cells ROB-C26 which is more primitive and less differentiated; 4) GDF-5 binds to distinct heterodimer of receptor for BMPs which is expressed more prevalently in less differentiated cells of mesenchymal origin.
This invention is directed to a method and composition for inducing or enhancing chondrogenesis in cells with an extracellular matrix containing GDF-5. The extracellular matrix consists of type I collagen, type II collagen, type I collagen plus hyaluronate or type II collagen plus hyaluronate, and contains growth and differentiation factor-5, GDF-5. An effective amount of GDF-5 to induce or enhance chondrogenesis is about 1 ng to 10 mg/ml matrix protein. A matrix is a solid porous composition having a relatively fixed three-dimensional structure.
Chondrogenesis is induced by an extracellular matrix composition of type I collagen, type II collagen, type I collagen plus hyaluronate, or type II collagen plus hyaluronate containing GDF-5. Type I and II collagen represent the most abundant ECM protein in bone and cartilage, respectively.
Collagen may be obtained from bone, tendons, skin, or the like. The collagen source may be any convenient animal source, mammalian or avian, including bovine, porcine, equine, or the like, or chicken, turkey or other domestic source of collagen.
Hyaluronic acid is a naturally-occuring polysaccharide containing alternating Nxcx9cacetylxcx9cDxcx9cglucosamine and Dxcx9cglucuronic acid monosaccharide units linked with beta 1-4 bonds and disaccharide units linked with beta 1-3 glycoside bonds. It occurs usually as the sodium salt and has a molecular weight range of about 50,000 to 8xc3x97106.
The collagen or collagen-hyalurate mixture is provided as a matrix, typically by lyophilization. The collagen-hyaluronate is formed by treating collagen with an active formyl aldehyde hyaluronate, formed as described in U.S. Pat. No. 5,866,165, incorporated by reference herein. The collagen hyaluronate composition is also provided as a matrix by lyophilization.
The matrix is preferably implanted with an effective amount of GDF-5, which is about 1 mg to 10 mg/ml of matrix protein.
To show in vitro application, fetal rat calvarial cells (FRC""s) were plated on various purified extracellular matrix proteins in the presence of recombinant human GDF-5 (100 ng/ml) for 3 weeks and scored for differentiation at the level of morphology, overall proteoglycan synthesis and deposition, and aggrecan and type II collagen expression. Results show that GDF-5 stimulated chondrogenic nodule formation of FRC""s plated only on type I or type II collagen. Chondrogenic nodules stained heavily with alcian blue and were positive for type II collagen and aggrecan-expression, as judged by immunohistochemical and transcriptional analyses. Cells in monolayer that surround the nodules were negative for the chondrogenic markers. In sharp contrast, GDF-5 failed to stimulate chondrogenesis in FRC""s plated on fibronectin, type IV collagen or tissue culture plastic.
Plastic plates were first coated with different ECM proteins including type I and II collagen, type IV collagen, or fibronectin. The results show that GDF-5 stimulated the formation of chondrogenic cell aggregate that bind heavily to the alcian blue stain. Under these conditions GDF-5 fails to stimulate the formation of characteristic nodules in FRC cultured in the presence of vehicle alone, type IV collagen, or fibronectin. Plastic culture 12 well (Costar, Cambridge, Mass.) were coated with 0.01% (w/v) of the indicated extracellular matrix proteins for 2 hours at 37Cxc2x0. After removal of nonadsorbant protein, fetal rat calvarial cells were plated at a density of 2xc3x97105 cells/well in DMEM containing 10% FBS. Culture plates were then maintained for 21 days in culture media supplemented with or without GDF-5 (100 ng/ml). Plates were then stained overnight with alcian blue stain (0.5% w/v in 3% acetic acid), washed and photographed. For quantitation of alcian blue, cells were solubilized in 8M urea, and the amount of stain was quantitated using spectrophotometer (Molecular Devices, Sunnyvale, Calif.). Since alcian blue is a cationic dye which has been shown to bind to anionic proteins including proteoglycans, these results suggest that GDF-5 induces a change in cellular morphology of a subpopulation of FRC.
To examine correlation of changes in cellular morphology with the process of chondrogenesis, total cellular RNA and protein were isolated from FRC culture treated with GDF-5 in the presence of type I collagen. Total cellular RNA isolated from FRC cells was subjected to a semiquantitative PCR analysis using specific primers designed to amplify aggrecan, type II collagen or type I collagen. Results show that expression of type II collagen and aggrecan mRNA is increased by around 2 and 3 respectively in cultures treated with GDF-5. Under these conditions, type I collagen mRNA expression decreased by about 20%. The expression of aggrecan and type II collagen was confirmed using slot blot analysis.
Total cell lysates (100 ug) were electrophoretically separated on a 8% or 5% SDSPAGE, transferred to immobilon-P and immunoblotted using antibody specific to type II collagen or aggrecan. The results show that GDF-5 stimulated a significant increase in the steady state level of type II collagen and aggrecan. Under these conditions GDF-5 fails to stimulate expression of type II collagen or aggrecan when FRC cells are cultured in the absence of type I collagen.
The collagen is also provided in matrix form for in vivo use. Type I collagen fibers were dispersed at 2% weight % ratio in distilled water and homogenized 3 times for 5 seconds each at low speed in a heavy duty blender. The pH of the slurry was then adjusted to a) pH 3.0; b) pH 7 0; or c) pH 10.0 by adding HCl or NaOH as necessary. The slurry was then cast into molds and frozen at the following temperatures prior to lyophilization:
a) pH 3.0 slurry: xe2x88x9278xc2x0 C., xe2x88x9240xc2x0 C. or xe2x88x9220xc2x0 C.
b) pH 7.0 slurry; xe2x88x9240xc2x0 C.
c) ph 10.0 slurry; xe2x88x9240xc2x0 C.
The lyophilization cycle for the above matrices was as follows: 0xc2x0 C. for 2 hours; xe2x88x9240xc2x0 C. for 2 hours; xe2x88x9220xc2x0 C. for 2 hours; xe2x88x924xc2x0 C. for 4 hours; and 25xc2x0 C. for 1 hour.
Hyaluronate containing active formyl aldehyde groups, prepared as disclosed in U.S. Pat. No. 5,866,165, was added to the above collagen matrices by immersion of the collagen matrix in a 2% weight % solution, pH 7-8 of the hyaluronate polyaldehyde. The immersed matrices were shaken at room temperature for 4 hours, washed 3 times and lyophilized using the lyophilization cycle described above for the collagen matrix preparation.
A porous matrix fabricated from type I collagen was seeded by, 1xc3x97105 cell per implant (2xc3x973xc3x973 mm). Cells embedded in matrices were then cultured for 3 weeks in culture supplemented with or without GDF-5 (100 ng/ml). Total RNA isolated from each implant were then subjected to RT-PCR. Results indicate that GDF-5 induced expression of aggrecan and type II collagen, two well known markers of chondrogenesis. In parallel the implant material was subject to histological evaluation followed by alcian or Toludine blue staining. Results show that GDF-5 was capable of inducing marked changes in cellular morphology of FRC underscored by increase in alcian blue staining and changes in cell shape. Under these conditions FRC cells were not able to proliferate and differentiate in the ECM in the absence of GDF-5 as measured by histological evaluation total DNA, RNA or protein content. These findings suggest that the GDF-5 biological response may be significantly enhanced by type I collagen possessing 3D matrix structure.
The surface property or the porosity of 3D collagen-based matrices were examined by preparing a series of implantable material possessing different porosity. Each matrix composite was either coated with or without hyaluronic acid, a major component of cartilage. The implants were then seeded with 1xc3x97105 cells per implant and cultured for 3 weeks in the presence of GDF-5 (100 ng/ml). Total RNA extracted from each implant were then subjected to semi-quantitative PCR analysis. Results indicate that FRC cells showed significant increase in the expression level of type II collagen and aggrecan when implanted only in matrices which were coated with hyaluronic acid and possessed the highest porosity (about 300 micron). Together these findings indicate that GDP-5 chondrogenesis activity is fully and potently synergized by a matrix which contain 1) high pore size (about 100-300 micron); and 2) is composed of type I collagen which is coated with hyaluronic acid.
The molecular signaling mechanism by which GDF-5 induces chondrogenesis in the context of type I collagen was also examined using well-characterized inhibitors of intracellular signaling mediators. Results show that the ligand-dependent chondrogenesis was completely inhibited by the calcium ionophore A23187 and rapamycin not by dibutyryl-cAMP, Na3VO4, or EGTA. The known inhibitory effect of rapamycin on activation of p70S6 kinase indicate that GDF-5/type I collagen-induced chondrogenesis is mediated through p70S6 kinase activation. The known effects of A23187 on intracellular calcium concentrations suggest that the GDF-5/type I collagen-induced chondrogenesis is mediated through a sustained decrease of intracellular calcium concentration.
These results indicate that cellular interaction with type I collagen significantly enhances the chondro-inductive activity of GDF-5. This effect is likely mediated by the convergence of downstream matrix and factor receptor signaling pathways.
The data indicates that GDF-5 biological function is modulated by a type I collagen extracellular matrix composition and structure containing GDF-5 that this event is regulated both temporally and spatially whereby one may regulate cellular morphogenesis and joint development in vivo.
The growth and differentiation factor-induced chondrogenesis is highly specific to GDF-5. It was shown that ECM-dependent chondrogenesis by GDF-5 is highly specific, by evaluating the ability of several mitogens and prototype differentiation factors under the following conditions. Chondrogenesis was assessed by monochromatic staining of FRC cultured in the presence of type I collagen and various growth factors. The results show that crude preparations of BMPs and TGFb, two other member of this class of differentiation factors, completely failed to stimulate chondrogenesis. In addition, growth factors including bFGF or IGF-I, IGF-II failed to stimulate chondrogenesis under these conditions. Together these findings suggest that the GDF-5 biological response may be distinguished from that shown by other members of TGFb superfamily.

Method of inducing or enhancing chondrogenesis with extracellular matrix containing GDF-5